1. Field of the Invention
The invention relates to a medium detection device and an image formation apparatus, such as a copy machine, a printer, a facsimile machine, or the like, having the same.
2. Description of Related Art
A conventional image formation apparatus such as a copy machine, a printer, a facsimile machine, or the like has a medium detection device provided at a predetermined position in a medium conveyance path and configured, when a recording medium such as paper is conveyed, to detect timing when the recording medium passes.
The image formation apparatus detects the time when the recording medium passes by using the medium detection device thereby detecting a delay of conveyance of the recording medium, an overlapped feed of the recording media, a medium jam, or the like. While monitoring the conveyance status of the recording medium in the apparatus, the image formation apparatus controls the entire image formation operation.
The medium detection device includes a rotatable sensor lever. When a recording medium reaches the medium detection device, the recording medium pushes the sensor lever to rotate about the rotational axis thereof. When the recording medium is passing therethrough, the sensor lever is rotated by the recording medium so that a detection area of an optical sensor such as a photo sensor is uncovered by the sensor lever turning the optical sensor into a light transmitting state. After the recording medium has passed therethrough, the sensor lever is returned to an initial position by weight of the sensor lever or a biasing force of a bias member such as a spring, covering the detection area of the optical sensor, thereby returning the optical sensor to a light blocking state.
An art relating to such a medium detection device is disclosed in Japanese Patent Application Laid-Open No. 2008-150149, for example.